This invention relates to an improved transmission mechanism for a gymnastic or exercise bicycle, in which the loaded fly wheel is mounted in parallel with the driving wheel on the same shaft. The transmission mechanism has one set of transmission wheels, whereby the rotation speed ratio between the driving wheel and the loaded fly wheel would reach 1:9. This transmission mechanism not only can increase the results of exercise, but also can reduce the dimensions of the loaded fly wheel, and therefore, the length of the transmission mechanism, and the length of the whole gymnastic bicycle as will.
At the present time, the gymnastic bicycle is a rather popular indoor exercise equipment. A user can drive the two pedals to rotate the loaded fly wheel, as if riding on a bicycle for gymnastic purpose. That kind of bicycle is usually to be operated at a stationary spot for fulfilling the gymnastic purpose. The conventional fly wheel of the gymnastic bicycle is usually furnished with a balance weight means. The diameters among the driving wheel, the loaded fly wheel, and the transmission wheel are different so as to require the user to pedal the bicycle with more physical force for obtaining exercise. As such bicycles are mainly used for indoor exercise, they are required to have the minimum dimensions with a maximum exercising efficiency; therefore, the driving wheel and the loaded fly wheel of conventional exercise bicycles have a rotation speed ratio of 1:3.
In the present invention, the transmission mechanism of the gymnastic bicycle has made a breakthrough in the rotation speed ratio of the conventional transmission mechanism in the gymnastic bicycle, and has had the rotation speed ratio raised up to 1:9, which reduces the length and dimensions of the bicycle so as to facilitate the installation, or handling or manufacturing thereof.